title: New conformational constraints in isotopically (13C) enriched oligosaccharides.
abstract: Multidimensional heteronuclear NMR studies have been applied to the resonance assignment and conformational analysis of 13C-enriched Neu5Acalpha2-3Galbeta1-4Glc. It is demonstrated that three-dimensional ROESY-HSQC experiments provide through-space distance restraints which cannot be observed with conventional homonuclear 1H techniques due to resonance overlap. In particular, connectivities demonstrating the existence of the "anti" conformation about the Galbeta1-4Glc glycosidic linkage are unambiguously observed. It is shown that 13C isotopic enrichment of the trisaccharide at a level >95% enables straightforward measurement of trans-glycosidic 1H-13C and 13C-13C coupling constants and a Karplus-type relation is derived for the latter. In total 15 conformational restraints were obtained for the trisaccharide in aqueous solution, all of which were in excellent agreement with theoretical parameters computed from a 5 ns molecular dynamics simulation of the glycan.
authors.affiliation: Centre for Biomolecular Sciences, University of St. Andrews, Fife, United Kingdom.
authors.forename: M J
authors.initials: MJ
authors.lastname: Milton
authors.forename: R
authors.initials: R
authors.lastname: Harris
authors.forename: M A
authors.initials: MA
authors.lastname: Probert
authors.forename: R A
authors.initials: RA
authors.lastname: Field
authors.forename: S W
authors.initials: SW
authors.lastname: Homans
mesh_terms: D018395:CA-19-9 Antigen; D002236:Carbohydrate Conformation; D002247:Carbon Isotopes; D005732:Gangliosides / Q000138:chemical synthesis / Q000737:chemistry; D007983:Lewis Blood Group Antigens / Q000737:chemistry; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D009844:Oligosaccharides / Q000737:chemistry* / Q000378:metabolism*; D011522:Protons; D012996:Solutions
chemical_list: D018395:CA-19-9 Antigen; D002247:Carbon Isotopes; D005732:Gangliosides; D007983:Lewis Blood Group Antigens; D009844:Oligosaccharides; D011522:Protons; D012996:Solutions; C064564:sialyl Le(a) ganglioside